A power gate circuit includes: a power gate switch connected at least between a reference potential terminal of a circuit to be power-gated and a reference potential or between a power supply terminal of the circuit to be power-gated and a power supply; a capacity connected to a gate of the power gate switch; a pulse generating section supplying a pulse signal to the gate of the power gate switch according to a control signal; and a power gate control section outputting the control signal to the pulse generating section to supply the pulse signal to the gate of the power gate switch when the power gate switch is turned on and accumulating electrical charges in the capacity to control a gate potential of the power gate switch such that the potential gradually approaches a potential at which the power gate switch is turned on.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A power gate circuit comprising: a power gate switch connected at least between a reference potential terminal of a circuit to be power-gated and a reference potential or between a power supply terminal of the circuit to be power-gated and a power supply; a capacitor connected to a gate of the power gate switch; a pulse generating section operable to supply a pulse signal to the gate of the power gate switch according to a control signal; and a power gate control section operable to output the control signal to the pulse generating section to supply the pulse signal to the gate of the power gate switch when the power gate switch is turned on and accumulate electrical charges in the capacitor to control a gate potential of the power gate switch such that the potential gradually approaches a potential at which the power gate switch is turned on, wherein the power gate control section sets the gate of the power gate switch to a constant potential instead of supplying the pulse signal after supplying the pulse signal for a predetermined period of time.
2. A power gate circuit according to claim 1 , wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal.
3. A power gate circuit according to claim 2 , wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal according to a mode signal.
4. A power gate circuit according to claim 1 , further comprising a switch connected between the constant potential and the gate of the power gate switch, wherein the power gate control section turns the switch on to connect the gate of the power gate switch to the constant potential instead of supplying the pulse signal after supplying the pulse signal for a predetermined period of time.
5. A solid-state imaging device comprising: a pixel section having a plurality of pixels performing photoelectric conversion arranged in the form of a matrix; and a pixel signal readout section operable to read pixel signals from the pixel section, the pixels being read in groups each formed by a plurality of pixels, the pixel signal readout section comprising an AD conversion portion performing analog-digital (AD) conversion, wherein the pixel signal readout section comprises: a plurality of comparators operable to compare a reference signal that is a ramp wave with the potential of an analog signal read out from a pixel of a column associated therewith, a plurality of counter latches disposed in association with the plurality of comparators, capable of counting the comparison times of the respective comparators, the counter latches operable to stop counting and hold count values when the output of the respective comparators is inverted, and a power gate circuit operable to serve the plurality of counter latch circuits, the power gate circuit comprising: a power gate switch connected at least between a reference potential terminal of a circuit to be power-gated and a reference potential or between a power supply terminal of the circuit to be power-gated and a power supply, a capacitor connected to a gate of the power gate switch, a pulse generating section operable to supply a pulse signal to the gate of the power gate switch according to a control signal, and a power gate control section operable to output the control signal to the pulse generating section to supply the pulse signal to the gate of the power gate switch when the power gate switch is turned on and accumulate electrical charges in the capacitor to control a gate potential of the power gate switch such that the potential gradually approaches a potential at which the power gate switch is turned on, wherein the power gate control section is operable to set the gate of the power gate switch to a constant potential instead of supplying the pulse signal after supplying the pulse signal for a predetermined period of time.
6. A solid-state imaging device according to claim 5 , wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal.
7. A solid-state imaging device according to claim 6 , wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal according to a mode signal.
8. A solid-state imaging device according to claim 5 , further comprising a switch connected between the constant potential and the gate of the power gate switch, wherein the power gate control section turns the switch on to connect the gate of the power gate switch to the constant potential instead of supplying the pulse signal after supplying the pulse signal for a predetermined period of time.
9. A camera system comprising: a solid-state imaging device; and an optical system operable to form an object image on the solid-state imaging element, the solid-state imaging device comprising: a pixel section comprising a plurality of pixels performing photoelectric conversion arranged in the form of a matrix, and a pixel signal readout section operable to read pixel signals from the pixel section, the pixels being read in groups each formed by a plurality of pixels, the pixel signal readout section comprising an AD conversion portion performing analog digital (AD) conversion, the pixel signal readout section further comprising: a plurality of comparators comparing a reference signal with the potential of an analog signal read out from a pixel of a column associated therewith in the pixel section, a plurality of counter latches disposed in association with the plurality of comparators, capable of counting the comparison times of the respective comparators, the counter latches operable to stop counting and hold count values when the output of the respective comparators is inverted, and a power gate circuit operable to serve the plurality of counter latch circuits, the power gate circuit comprising: a power gate switch connected at least between a reference potential terminal of a circuit to be power-gated and a reference potential or between a power supply terminal of the circuit to be power-gated and a power supply, a capacitor connected to a gate of the power gate switch, a pulse generating section operable to supply a pulse signal to the gate of the power gate switch according to a control signal, and a power gate control section operable to output the control signal to the pulse generating section to supply the pulse signal to the gate of the power gate switch when the power gate switch is turned on, wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal.
10. The camera system according to claim 9 , wherein the power gate control section is operable to accumulate electrical charges in the capacitor to control a gate potential of the power gate switch such that the potential gradually approaches a potential at which the power gate switch is turned on.
11. The camera system according to claim 9 , wherein the power gate control section is operable to change the pulse width of the pulse signal from the pulse generating section using the control signal according to a mode signal.
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August 30, 2011
December 10, 2013
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